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Investigators are attempting to piece together the events -- including a series of carjackings -- that led to the deaths of four people Tuesday morning in Orange County. Annette Arreola and Vikki Vargas report for the NBC4 News at Noon on Tuesday Feb. 19, 2013. (Published Tuesday, Feb 19, 2013)

Updated at 6:57 PM EDT on Tuesday, Feb 19, 2013

Four people are dead after a series of shootings and carjackings early Tuesday near the 55 Freeway in southern California's Orange County that began after the shooting death of a woman at a home.

OC Shootings Began in Ladera Ranch

Authorities discussed the events that led to a series of shooting deaths and carjackings early Tuesday in Orange County. Raw video broadcast Feb. 19, 2013. (Published Tuesday, Feb 19, 2013)

The gunman was identified as Ali Syed, a 20-year-old who lived at the home with his parents. Syed died from a self-inflicted gunshot at an intersection in Orange after a series of carjackings and freeway shootings, according to Orange County authorities.

"There are no other shooters and there is no threat to the community," said Orange County Sheriff's Department spokesman Jim Amormino.

Investigators responded to at least five locations in connection with the carjackings and shootings, including a home on Red Leaf Lane in Ladera Ranch where police said Syed shot and killed a woman in her 20s.

"I heard the pops, and didn’t know what it was, and then the cops showed up a couple of hours later," said neighbor Jason Glass.

The victim was "shot multiple times," Amormino said. The victim's identity and relationship to the gunman -- a student at Saddleback College -- were not available Tuesday afternoon, but Amormino said she is not Syed's mother.

"It's not known at this time what she was doing in the residence," Amormino said.

Responding deputies were notified the gunman left the residence in his parents' black sport utility vehicle.

The police response in the Tustin area -- about 20 miles north of Ladera Ranch -- began with a carjacking and shots fired report at about 5:10 a.m. near Red Hill and Nisson Road, just off the 5 Freeway. A man was waiting in a vehicle in a Denny's parking lot when he noticed Syed loading a shotgun.

"(The victim) quickly got back into his car and accelerated rapidly," said Tustin Police Chief Scott Jordan. "At the same time, Mr. Syed got out of his car and started shooting into the back of his window, almost as if he was chasing him on foot."

The driver was shot in the back of the head, but drove from the scene, police said.

Syed -- police said he has no prior criminal record -- left the location in the black SUV, which sustained damage, including a flat tire. It was not clear how the SUV was damaged.

Syed abandoned the vehicle and approached a man at a nearby fuel station.

The man handed Syed the key to his pickup, which he drove north on the 5 Freeway to the southbound 55 Freeway. Three motorists reported injuries after Syed opened fire at vehicles on the freeway, police said.

Syed returned to the pickup and drove to the Village Way exit in Santa Ana, where a second carjacking and occurred. The carjacking victim was killed in what police described as an execution.

"He confronted our victim, who was in his BMW, and ordered him out of the vehicle," said Santa Ana Police Corporal Anthony Bertagna. "He walks him to the side of the curb and executes our victim."

Aerial video showed a pickup and several patrol vehicles on the exit ramp from the 55 Freeway. The victim was shot three times, Jordan said.

The shooting victim was identified as Melvin Edwards, 69, of Laguna Hills. Edwards was on his way to work in Santa Ana, said Santa Ana Police Chief Carlos Rojas.

The gunman drove to a nearby Micro Center electronics store parking lot near Edinger Avenue and Newport Avenue in the victim's BMW, then carjacked another driver, police said. Officers discovered two gunshot victims at the Micro Center, one of whom was pronounced dead at the scene just east of the 55 Freeway.

The deceased victim was identified as Jeremy Lewis, 27, of Fullerton.

Colleagues told NBC4 the victims at the Micro Center lot worked for a plumbing contractor in Rancho Cucamonga. Lewis was shot and killed was just arriving for work at a hotel near the Micro Center. Lewis' co-worker suffered a graze wound to the arm when he responded to the gunfire.

"It was his vehicle that Mr. Syed then entered," Jordan said. "Many calls were coming in and the California Highway Patrol got in behind the stolen vehicle."

The quickly developing situation came to an end in Orange, when Syed exited onto eastbound Katella Avenue. Syed "almost instantly" shot himself in the head when he got out of the moving vehicle, Jordan said.